import type { SparkleAreaOptions } from "./types";
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/**
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* Generate a random position for a sparkle within an area, avoiding a cutout in the center.
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*/
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export function randomPositionAvoidingCenter(options: SparkleAreaOptions): { top: number; left: number } {
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const {
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areaShape,
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areaWidth = 28,
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areaHeight = 28,
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areaRadius = 14,
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cutoutShape,
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cutoutWidth = 0,
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cutoutHeight = 0,
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cutoutRadius = 12,
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center,
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} = options;
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for (let i = 0; i < 10; i++) {
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let top: number;
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let left: number;
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if (areaShape === "circle") {
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const angle = Math.random() * 2 * Math.PI;
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const r =
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cutoutShape === "circle"
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? cutoutRadius + Math.random() * (areaRadius - cutoutRadius)
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: Math.random() * areaRadius;
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top = center.y + r * Math.sin(angle);
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left = center.x + r * Math.cos(angle);
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} else {
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// areaShape === 'rect'
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top = center.y - areaHeight / 2 + Math.random() * areaHeight;
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left = center.x - areaWidth / 2 + Math.random() * areaWidth;
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}
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// Check if inside cutout
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let inCutout = false;
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if (cutoutShape === "circle") {
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const dx = left - center.x;
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const dy = top - center.y;
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if (Math.sqrt(dx * dx + dy * dy) < cutoutRadius) inCutout = true;
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} else if (cutoutShape === "rect") {
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if (
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left > center.x - cutoutWidth / 2 &&
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left < center.x + cutoutWidth / 2 &&
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top > center.y - cutoutHeight / 2 &&
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top < center.y + cutoutHeight / 2
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) {
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inCutout = true;
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}
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}
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// Check if inside area
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let inArea = true;
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if (areaShape === "circle") {
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const dx = left - center.x;
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const dy = top - center.y;
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if (Math.sqrt(dx * dx + dy * dy) > areaRadius) inArea = false;
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} else if (areaShape === "rect") {
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if (
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left < center.x - areaWidth / 2 ||
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left > center.x + areaWidth / 2 ||
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top < center.y - areaHeight / 2 ||
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top > center.y + areaHeight / 2
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) {
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inArea = false;
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}
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}
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if (!inCutout && inArea) {
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return { top, left };
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}
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}
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// fallback: center of area
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return { top: center.y, left: center.x };
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}
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